If you take a plastic garbage can with a lid, you can make a trap.

Cut a hole in the lid about the size of a pop/soda can. Throw a brick or two in the can. Then secure the lid to the can with some wire ties or what not. Also poke some holes randomly around the whole can/lid so it won't hold air.

Tie a rope to one of the handles.

Then throw some nasty bait into the can like old meats, hot dogs, chicken livers, road kill, etc. Maybe even some fish food pellets if you have them.

Huck the trap out in the water to where it will sit on the bottom in a few feet of water (3-5'), and let it sit for a few hours.

Then come back and quickly haul the can out of the water, fast enough so no nasty bullhead can swim out.

Check the trap and see what you have. If nothing, try a different location or bait.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."